Oskar Dunn-Koczorowski, left, and Michael Szewczuk were sentenced at the Old Bailey Tuesday.
London CNN  — 

A far-right teenager who reportedly branded Prince Harry a “race traitor” and suggested he should be shot after his marriage to Meghan Markle has been jailed in Britain for four years and three months.

Michal Szewczuk, 19, posted extremist material including an image of the prince with a gun to his head on a blood-spattered background, the UK Press Association (PA) news agency reported.

Published months after Harry’s wedding to Meghan, whose mother is African-American, the image also featured a swastika and the phrase: “See Ya Later Race Traitor.”

Szewczuk was sentenced at the Old Bailey in London Tuesday, after pleading guilty to two counts of encouraging terrorism and five accounts of possessing terrorist material, the UK’s Counter Terrorism Policing (CTP) unit confirmed in a statement.

Among the materials in Szewczuk’s possession was the White Resistance Manual – a white supremacist handbook – and the al Qaeda Training Manual, PA said.

Michael Szewczuk reportedly branded Prince Harry a "race traitor" in online posts.

Szewczuk, who is of Polish descent but lives in Leeds, northern England, also wrote an “extremely violent and aggressively misogynistic” blog which attempted to justify the rape of women and children in the pursuit of an Aryan race, the court heard.

The 19-year-old is to be detained in a young offenders institution, PA reported.

He was sentenced alongside Oskar Dunn-Koczorowski, 18, from West London, who received an 18-month detention and training order after admitting to two counts of encouraging terrorism, CTP confirmed.

Dunn-Koczorowski’s posts included support for Anders Breivik, the Norwegian far-right terrorist who killed 77 people in 2011, and material threatening the ethnic cleansing of Albanians.

Detective Chief Superintendent Martin Snowden, who is head of CTP North East, said that Szewczuk and Dunn-Koczorowski “see themselves as superior to the majority of society” and “feel their duty is to express their beliefs, in turn teaching others.”

“The considerable amount of material they have posted on social media channels not only reflects their extremist beliefs but was intended to encourage others to carry out despicable acts,” he said in a statement seen by CNN.

“Both men have developed and evolved their interest in the extreme right-wing ideology over time through research and connecting with like-minded individuals.”

Judge Rebecca Poulet, who presided over the case, described Szewczuk’s images as “abhorrent as well as criminal by reason of their intention to encourage terrorist acts.”

“Individuals were urged to go out and commit appalling acts of violence on others for no reason that can ever be understood by any right-thinking individuals,” she told Szewczuk in court, according to PA.

When handing down the sentence to Dunn-Koczorowski, Poulet noted that he still held “deeply entrenched views in support of this extreme right-wing ideology.” This was echoed by his lawyer, David Kitson, who pointed to a medical report which stated that the teenager had a “lack of remorse.”

Naomi Parsons, the prosecutor in the case, said that the pair’s posts “convey a message of the threat of and/or use of serious violence against others, in order to advance a political, ideological and racial cause and in this way encourage terrorism.”

She added that the targets of their posts included non-white people, the Jewish population and anyone “perceived to be complicit in the perpetuation of multi-culturalism.”

The defendants, who had only met each other online, were arrested last December as part of a pre-planned police operation, the CTP said.

Szewczuk, who was studying computer science at Portsmouth University, was arrested at his halls of residence, while Dunn-Koczorowski was detained at his home in London.

CNN’s Max Ramsay contributed to this report.